JP7322335B2 - Method for producing rubber composition - Google Patents

Description

The present invention relates to a method for producing a rubber composition, and also to a method for producing a tire.

In tires, a rubber composition excellent in low heat build-up is required in order to improve fuel efficiency. Modified diene rubbers, silane coupling agents, dispersants, etc. are used to improve low heat build-up.

Patent Document 1 discloses that a tetrazine compound is used as a dispersant for silica, and the low heat build-up is improved by masterbatching the tetrazine compound with a diene rubber.

WO2017/057758

However, it has been found that when a tetrazine compound is added to a diene rubber to produce a masterbatch, the viscosity of the unvulcanized rubber composition produced using the masterbatch increases, impairing processability.

In view of the above points, an embodiment of the present invention is a method for producing a rubber composition that can suppress an increase in the viscosity of an unvulcanized rubber composition while maintaining excellent low heat build-up due to the use of a tetrazine compound. intended to provide

A method for producing a rubber composition according to an embodiment of the present invention includes a first mixing step of adding carbon black and a tetrazine compound to a first diene rubber, mixing them in a kneader and discharging the mixture, and the first mixing step. and a second mixing step of adding the second diene rubber and silica to the mixture obtained in step 1, mixing them in a kneader, and discharging the mixture.

A method for producing a tire according to an embodiment of the present invention comprises producing a rubber composition by the production method, producing an unvulcanized tire using the obtained rubber composition, and obtaining an unvulcanized tire. vulcanizing the sulfur tire.

According to the embodiment of the present invention, it is possible to suppress an increase in the viscosity of the unvulcanized rubber composition while maintaining excellent low heat build-up due to the use of the tetrazine compound.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail.

A rubber composition according to an embodiment contains a diene rubber as a rubber component, a tetrazine compound, silica, and carbon black.

The diene rubber used as the rubber component is not particularly limited, and examples include natural rubber (NR), synthetic isoprene rubber (IR), polybutadiene rubber (BR), styrene butadiene rubber (SBR), nitrile rubber (NBR), Commonly used in rubber compositions such as chloroprene rubber (CR), butyl rubber (IIR), halogenated butyl rubber, styrene-isoprene copolymer rubber, butadiene-isoprene copolymer rubber, styrene-isoprene-butadiene copolymer rubber Various types are mentioned and these can be used individually by any one type or in combination of 2 or more types. Among these, the diene rubber preferably contains at least one selected from the group consisting of natural rubber, polybutadiene rubber and styrene-butadiene rubber.

Specific examples of the diene rubbers listed above include at least one group selected from the group consisting of amino groups, hydroxy groups, alkoxy groups, epoxy groups, silyl groups, and carboxy groups at the molecular terminal or in the molecular chain. Modified diene-based rubbers modified by the functional groups introduced by the introduction of the functional groups of the species are also included. By including the modified diene rubber in the diene rubber, when silica is used as a filler, its dispersibility can be improved. Modified styrene-butadiene rubber is preferably used as the modified diene rubber. Therefore, the diene rubber according to one embodiment contains a styrene-butadiene rubber having at least one functional group selected from the group consisting of amino groups, hydroxyl groups, alkoxy groups, epoxy groups, silyl groups and carboxy groups. is.

A tetrazine compound is a general term for compounds containing a tetrazine ring, and includes tetrazine and its derivatives. As the tetrazine compound, it is preferable to use a compound represented by the following general formula (1) or a salt thereof.

In the formula, R ¹ and R ² each independently represent a hydrogen atom, an alkyl group, an alkylthio group, an aralkyl group, an aryl group, an arylthio group, a heterocyclic group or an amino group, each of which is substituted with one or more You may have a group.

The alkyl group may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group is preferably 1-8. More preferred alkyl groups are linear or branched alkyl groups having 1 to 6 carbon atoms.

The alkylthio group may be linear, branched or cyclic. The alkylthio group preferably has 1 to 8 carbon atoms. A more preferred alkylthio group is a linear or branched alkylthio group having 1 to 6 carbon atoms.

The aralkyl group includes, for example, benzyl group, phenethyl group, trityl group, 1-naphthylmethyl group and the like.

The aryl group includes, for example, a phenyl group, a biphenyl group, a naphthyl group and the like.

The arylthio group includes, for example, a phenylthio group, a biphenylthio group, a naphthylthio group and the like.

Examples of heterocyclic groups include pyridyl, pyrazinyl, pyrimidyl, pyridazyl, quinolyl, isoquinolyl, quinoxalinyl, quinazolinyl, phthalazinyl, tetrahydroquinolyl, pyrrolyl, imidazolyl, pyrazolyl, and indolyl. Nitrogen-containing heterocyclic groups such as groups, benzimidazolyl groups and indazolyl groups; Oxygen-containing heterocyclic groups such as furyl groups, benzofuranyl groups and isobenzofuranyl groups; Sulfur-containing heterocyclic groups such as thienyl groups and benzothienyl groups; heterocyclic groups containing nitrogen and oxygen atoms such as , isoxazolyl and benzoxazolyl groups; and heterocyclic groups containing nitrogen and sulfur atoms such as thiazolyl, isothiazolyl and benzothiazolyl. Among these, a heteroaromatic ring group that is a heterocyclic group having aromaticity is preferred, and pyridyl, pyrimidyl, pyrazinyl, pyrazolyl, furyl, or thienyl is more preferred.

The amino group may be not only a primary amino group (—NH ₂ ) but also a secondary or tertiary amino group having one or two hydrocarbon groups (preferably alkyl groups). In the case of a secondary or tertiary amino group, the total number of carbon atoms in the hydrocarbon group is preferably 15 or less.

Each of these alkyl groups, alkylthio groups, aralkyl groups, aryl groups, arylthio groups, heterocyclic groups and amino groups may have one or more substituents. The substituent is not particularly limited, and examples thereof include a halogen atom, an amino group, an aminoalkyl group, an alkoxycarbonyl group, an acyl group, an acyloxy group, an amide group, a carboxyl group, a carboxyalkyl group, a formyl group, a nitrile group, a nitro groups, alkyl groups, hydroxyalkyl groups, hydroxyl groups, alkoxy groups, aryl groups, aryloxy groups, heterocyclic groups, thiol groups, alkylthio groups, arylthio groups and the like. The substituent may preferably have 1 to 5, more preferably 1 to 3.

The salt of the tetrazine compound represented by formula (1) is not particularly limited, and examples thereof include inorganic acid salts such as hydrochlorides, sulfates, and nitrates; organic acid salts such as acetates and methanesulfonates; and sodium salts. alkali metal salts such as , potassium salts; alkaline earth metal salts such as magnesium salts and calcium salts; quaternary ammonium salts such as dimethylammonium and triethylammonium salts;

In one embodiment, since the tetrazine compound can increase the reactivity of the Diels-Alder reaction with the carbon-carbon double bond of the diene rubber, R ¹ and R ² in formula (1) are Each independently is preferably an aryl group or a heterocyclic group, more preferably a heterocyclic group, still more preferably a nitrogen-containing heteroaromatic group, and particularly preferably a pyridyl group.

The amount of the tetrazine compound is not particularly limited, but is preferably 0.1 to 10 parts by mass, more preferably 0.2 to 5 parts by mass, more preferably 0.3 to 0.3 parts by mass, based on 100 parts by mass of the rubber component. It may be 2 parts by mass.

Silica as a filler is not particularly limited, and for example, wet silica such as wet sedimentation silica and wet gel silica may be used.

The amount of silica compounded is not particularly limited, but it is preferably 10 to 120 parts by mass, more preferably 15 to 100 parts by mass, and still more preferably 20 to 80 parts by mass based on 100 parts by mass of the rubber component. Yes, and may be 30 to 60 parts by mass.

Carbon black as a filler is not particularly limited, and various known varieties can be used. Examples include SAF grade (N100 series), ISAF grade (N200 series), HAF grade (N300 series), FEF grade (N500 series) (both ASTM grades), and the like. These grades of carbon black can be used singly or in combination of two or more.

The amount of carbon black is not particularly limited, but it is preferably 10 to 120 parts by mass, more preferably 15 to 100 parts by mass, and still more preferably 20 to 80 parts by mass based on 100 parts by mass of the rubber component. and may be 30 to 60 parts by mass.

In addition to the above components, the rubber composition according to the present embodiment includes a silane coupling agent, zinc oxide, oil, stearic acid, anti-aging agent, wax, vulcanizing agent, vulcanization accelerator, etc. Various commonly used additives can be blended.

Silane coupling agents include sulfide silane and mercapto silane. The amount of the silane coupling agent compounded is not particularly limited, but it is preferably 2 to 20% by mass based on the amount of silica compounded.

Sulfur is preferably used as the vulcanizing agent. The amount of the vulcanizing agent is not particularly limited, but it is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, per 100 parts by mass of the rubber component. Examples of vulcanization accelerators include various vulcanization accelerators such as sulfenamide-based, thiuram-based, thiazole-based, guanidine-based, and dithiocarbamate-based vulcanization accelerators. They can be used in combination. The amount of the vulcanization accelerator is not particularly limited, but it is preferably 0.1 to 7 parts by mass, more preferably 0.5 to 5 parts by mass based on 100 parts by mass of the rubber component. .

A method for producing a rubber composition according to an embodiment includes the following first mixing step and second mixing step, and usually further includes the following third mixing step.
- A first mixing step of adding carbon black and a tetrazine compound to the first diene rubber, mixing them in a kneader, and discharging the mixture.
- A second mixing step of adding a second diene rubber and silica to the mixture obtained in the first mixing step, mixing the mixture with a kneader, and discharging the mixture.
- A third mixing step of adding and mixing a vulcanizing agent to the mixture obtained in the second mixing step.

Here, as the kneader, various known rubber kneaders such as a Banbury mixer, which is a closed type kneader, can be used. The same kneader may be used in any two kneading steps or all the kneading steps, or different kneaders may be used in each kneading step.

In the first mixing step, the first diene rubber, the carbon black and the tetrazine compound are added to the kneader and kneaded. When kneading, the temperature rises due to heat generation due to shearing, so the mixture is discharged from the kneader at a predetermined first discharge temperature.

The first mixing step is a step of forming a masterbatch from the first diene rubber and the tetrazine compound, and in the present embodiment, carbon black is further added to form a masterbatch. As a result, the affinity of the rubber component for the silica added in the second mixing step can be improved, and the dispersibility of silica can be improved. Viscosity increase can be suppressed.

As the first diene-based rubber used in the first mixing step, one or more of the diene-based rubbers described above can be used, preferably at least one rubber selected from the group consisting of natural rubber, polybutadiene rubber and styrene-butadiene rubber. It is to contain seeds.

In one embodiment, the first diene-based rubber preferably contains styrene-butadiene rubber from the viewpoint of low heat build-up and effect of suppressing viscosity increase. In that case, the first diene-based rubber preferably contains 50% by mass or more, more preferably 80% by mass or more of styrene-butadiene rubber, based on the total amount of the first diene-based rubber being 100% by mass. Rubber alone may be used.

The amount of carbon black added in the first mixing step is preferably 10 to 80 parts by mass, more preferably 20 to 70 parts by mass, and still more preferably 30 parts by mass with respect to 100 parts by mass of the first diene rubber. ~60 parts by mass. By increasing the amount of carbon black added in the first mixing step, the effect of suppressing the increase in viscosity of the unvulcanized rubber composition can be enhanced.

The amount of the tetrazine compound added in the first mixing step is preferably 0.1 to 10 parts by mass, more preferably 0.2 to 5 parts by mass with respect to 100 parts by mass of the first diene rubber, More preferably, it is 0.3 to 2 parts by mass. By increasing the amount of the tetrazine compound added in the first mixing step, the effect of improving the low heat build-up property can be enhanced, and the effect of suppressing the viscosity increase of the unvulcanized rubber composition can be enhanced.

Since the first mixing step is a masterbatching step as described above, it is preferable not to add other components, but other components such as oil may be added as long as the effects of the present embodiment are not impaired may In addition, a vulcanizing agent and a vulcanization accelerator are not added in the first mixing step.

Although the first discharge temperature is not particularly limited, it is preferably 80 to 190°C, more preferably 90 to 160°C, still more preferably 100 to 150°C, and particularly preferably 120 to 140°C. is. The mixing time is not particularly limited, and may be, for example, 30 seconds to 20 minutes, 1 minute to 10 minutes, or 3 minutes to 8 minutes. The mixture discharged from the kneader is usually cooled by being left at room temperature. At that time, the cooling effect can be enhanced by stretching the mixture into a sheet.

In the second mixing step, the mixture obtained in the first mixing step is charged into a kneader, and the second diene rubber and silica are charged and kneaded. When kneading, the temperature rises due to heat generation due to shearing, so the mixture is discharged from the kneader at a predetermined second discharge temperature.

As the second diene-based rubber used in the second mixing step, one or more of the diene-based rubbers described above can be used, and preferably at least one selected from the group consisting of natural rubber, polybutadiene rubber and styrene-butadiene rubber. It is to contain seeds, and more preferably, to use natural rubber and/or polydiene rubber. As the second diene rubber, the same diene rubber as the first diene rubber may be used, but usually a diene rubber different from the first diene rubber is used.

In one embodiment, the second diene-based rubber preferably comprises natural rubber. In that case, the second diene rubber preferably contains 50% by mass or more, more preferably 80% by mass or more of natural rubber, based on the total amount of the second diene rubber being 100% by mass. It's okay.

The ratio of the first diene rubber (the first diene rubber contained in the mixture obtained in the first mixing step) and the second diene rubber introduced in the second mixing step is not particularly limited. The mass ratio of the first diene rubber/second diene rubber is preferably 20/80 to 90/10, more preferably 30/70 to 80/20, and still more preferably 50/50 to 70. /30.

The amount of silica added in the second mixing step is not particularly limited, but it is preferably 10 to 120 parts by mass with respect to 100 parts by mass of the rubber component (the total of the first diene rubber and the second diene rubber). , more preferably 15 to 100 parts by mass, more preferably 20 to 80 parts by mass, and may be 30 to 60 parts by mass.

In the second mixing step, other fillers such as carbon black may be introduced along with silica. The amount of carbon black added in the second mixing step is not particularly limited, but the total amount of carbon black added in the first mixing step is 10 to 120 mass parts per 100 parts by mass of the rubber component as described above. parts, more preferably 15 to 100 parts by mass, still more preferably 20 to 80 parts by mass, and particularly preferably 30 to 60 parts by mass.

In the second mixing step, it is preferable to add additives such as a silane coupling agent, zinc oxide, oil, stearic acid, anti-aging agent and wax in addition to the above components. However, since the second mixing step is a non-pro-kneading step, neither a vulcanizing agent nor a vulcanization accelerator is added.

Although the second discharge temperature is not particularly limited, it is preferably 100 to 190.degree. C., more preferably 120 to 180.degree. C., and even more preferably 130 to 170.degree. Preferably, the second discharge temperature is higher than the first discharge temperature. The mixing time is not particularly limited, and may be, for example, 30 seconds to 15 minutes, or 1 minute to 10 minutes. The mixture discharged from the kneader is usually cooled by being left at room temperature. At that time, the cooling effect can be enhanced by stretching the mixture into a sheet.

In the third mixing step, the mixture obtained in the second mixing step is charged into a kneader, and a vulcanizing agent is added for kneading. When kneading, the temperature rises due to heat generation due to shearing, so the mixture is discharged from the kneader at a predetermined third discharge temperature. Thereby, an unvulcanized rubber composition can be prepared.

Since the third mixing step is a professional kneading step, it is preferable to add a vulcanization accelerator together with the vulcanizing agent. In addition, in the third mixing step, additives other than the vulcanizing agent and the vulcanization accelerator may be blended.

The amounts of the vulcanizing agent and the vulcanization accelerator added in the third mixing step can be set as described above as the compounding amounts in the rubber composition.

In the third mixing step, the discharge temperature (third discharge temperature) is preferably set lower than the first and second discharge temperatures in order to suppress the reaction between the vulcanizing agent and the vulcanization accelerator. The third discharge temperature is preferably set at less than 120°C, more preferably 80-110°C, even more preferably 90-100°C.

The rubber composition thus obtained can be used for various rubber members such as tires, anti-vibration rubbers and conveyor belts.

A tire manufacturing method according to an embodiment includes the following steps.
- A step of producing a rubber composition by the above production method,
- A step of producing an unvulcanized tire (green tire) using the obtained rubber composition, and
- A step of vulcanizing and molding the obtained unvulcanized tire.

Each step of preparing an unvulcanized tire and vulcanization molding is not particularly limited, and a tire can be manufactured using the rubber composition according to a conventional method.

When the rubber composition is used in a tire, it is applied to various parts of the tire such as the tread portion and sidewall portion. That is, a tire according to one embodiment includes a tread rubber made of the above rubber composition. Examples of tires include pneumatic tires of various sizes and for various applications such as tires for passenger cars and heavy-duty tires for trucks and buses.

In one embodiment, a pneumatic tire comprising a tread rubber made of the above rubber composition is produced by molding the rubber composition into a tread rubber having a predetermined shape by extrusion or the like according to a conventional method, and combining it with other parts. After producing a vulcanized tire, it can be produced by vulcanizing and molding an unvulcanized tire at 140 to 180° C., for example.

The tread rubber of a tire includes a two-layer structure consisting of a cap rubber and a base rubber, and a single-layer structure in which the two are integrated. That is, if the tread rubber has a single-layer structure, the tread rubber is preferably made of the above rubber composition, and if it has a two-layer structure, the cap rubber is preferably made of the above rubber composition.

Examples are shown below, but the present invention is not limited to these examples.

[Preparation of masterbatch (first mixing step)]
According to the composition (parts by mass) shown in Table 1 below, styrene-butadiene rubber was put into a Banbury mixer, then carbon black and a tetrazine compound were added and mixed. was changed to maintain 120° C. and mixed for 5 minutes. The mixture was then discharged at 120°C. After the mixture was stretched into a sheet, it was allowed to cool to room temperature to obtain masterbatches 1-8.

Details of each component in Table 1 are as follows.
・SBR1: "JSR1723" manufactured by JSR Corporation (emulsion polymerization SBR, oil-extended rubber: containing 37.5 parts by mass of oil per 100 parts by mass of solid rubber)
・SBR2: "JSR0122" manufactured by JSR Corporation (emulsion polymerization SBR, oil-extended rubber: containing 34 parts by mass of oil per 100 parts by mass of solid rubber)
・ SBR3: "HPR350" manufactured by JSR Corporation (alkoxy group and amino group terminal modified solution polymerization SBR)
・ Carbon black: HAF, Tokai Carbon Co., Ltd. “SEAST 3”
Tetrazine compound: 3,6-di(2-pyridyl)-1,2,4,5-tetrazine, manufactured by Tokyo Chemical Industry Co., Ltd.

［ゴム組成物の調製及び評価］
第２混合工程として、下記表２～４に示す配合（質量部）に従って、バンバリーミキサーに、硫黄と加硫促進剤を除く成分を投入し、４分間混合して第２排出温度（１５０℃）で混合物を排出した。該混合物をシート状に引き伸ばした後、常温下に放置して冷却した。次いで、第３混合工程として、バンバリーミキサーに該混合物を投入し、硫黄と加硫促進剤を添加して１分間混合し、第３排出温度（９０℃）で混合物を排出することにより、各ゴム組成物を得た。

[Preparation and Evaluation of Rubber Composition]
In the second mixing step, ingredients other than sulfur and a vulcanization accelerator were added to a Banbury mixer according to the formulations (mass parts) shown in Tables 2 to 4 below, and mixed for 4 minutes to reach the second discharge temperature (150 ° C.). The mixture was discharged at . After the mixture was stretched into a sheet, it was allowed to stand at room temperature to cool. Next, as a third mixing step, the mixture is put into a Banbury mixer, sulfur and a vulcanization accelerator are added, mixed for 1 minute, and the mixture is discharged at the third discharge temperature (90 ° C.) to obtain each rubber. A composition was obtained.

In addition, in the examples and the comparative examples, the rubber component was set to have a composition of SBR/NR = 60/40 (parts by mass) in order to easily compare the effects. In addition, the blending amount of carbon black, including the amount derived from the masterbatch, was set to 40 parts by mass (per 100 parts by mass of the rubber component).

Details of each component in Tables 2 to 4 are as follows.
- SBR1, SBR2, SBR3, Carbon Book: Same as Table 1.
- Masterbatches 1 to 8: those prepared in Table 1.
・NR: RSS#3
・ Silica: "Ultrasil VN3" manufactured by Evonik Industries
・ Silane coupling agent: “Si69” manufactured by Evonik Industries
・ Oil: “Process NC140” manufactured by JXTG Energy Co., Ltd.
・ Zinc oxide: Mitsui Kinzoku Mining Co., Ltd. “Zinc oxide type 2”
・ Anti-aging agent: "Antigen 6C" manufactured by Sumitomo Chemical Co., Ltd.
・ Stearic acid: “Lunac S-20” manufactured by Kao Corporation
・Wax: "OZOACE0355" manufactured by Nippon Seiro Co., Ltd.
・ Sulfur: “5% oil-containing fine powder sulfur” manufactured by Tsurumi Chemical Industry Co., Ltd.
・ Vulcanization accelerator 1: "Sokushinol CZ" manufactured by Sumitomo Chemical Co., Ltd.
- Vulcanization accelerator 2: "Noccellar D" manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.

For each rubber composition obtained, the viscosity in an unvulcanized state was measured, and a test piece having a predetermined shape was prepared by vulcanizing at 160°C for 30 minutes. Pyrogenicity was evaluated. Each measurement/evaluation method is as follows.

・Viscosity: According to JIS K6300, using a Mooney Viscometer manufactured by Shimadzu Corporation, unvulcanized rubber is preheated at 100°C for 1 minute, and the torque value after 4 minutes is measured in Mooney units. In Table 3, the value of Comparative Example 1 is shown as 100, and in Table 4, the value of Comparative Example 4 is shown as 100. The smaller the index, the lower the Mooney viscosity and the better the workability.

・ Low heat build-up: Using a viscoelasticity tester manufactured by Toyo Seiki Co., Ltd., the loss factor tan δ was measured under the conditions of a frequency of 10 Hz, a static strain of 10%, a dynamic strain of 1%, and a temperature of 60 ° C. Table 2 compares The value of Example 1, the value of Comparative Example 3 in Table 3, and the value of Comparative Example 4 in Table 4 are shown as 100, respectively. A smaller index indicates less heat generation, lower rolling resistance in the tire, and better rolling resistance performance (that is, fuel efficiency).

結果は表２～４に示す通りである。表２に示すように、テトラジン化合物を配合していない比較例１に対し、テトラジン化合物を予めマスターバッチ化して配合した比較例２では低発熱性は改善されたものの、未加硫ゴム粘度が増加した。これに対し、テトラジン化合物をカーボンブラックとともにスチレンブタジエンゴムとマスターバッチ化した実施例１～５であると、比較例２に対して低発熱性を維持ないし更に改善しながら、粘度が大幅に低下しており、低発熱性と加工性を高度に両立させることができた。

The results are shown in Tables 2-4. As shown in Table 2, in comparison with Comparative Example 1 in which no tetrazine compound was blended, in Comparative Example 2 in which a tetrazine compound was masterbatched in advance, low heat build-up was improved, but the unvulcanized rubber viscosity increased. bottom. On the other hand, in Examples 1 to 5 in which the tetrazine compound was masterbatched with styrene-butadiene rubber together with carbon black, the viscosity was significantly reduced while maintaining or further improving the low heat build-up compared to Comparative Example 2. It was possible to achieve both low heat build-up and workability at a high level.

Further, as shown in Tables 3 and 4, even when the type of rubber component was changed, Examples 6 and 7, in which a tetrazine compound was masterbatched with carbon black and styrene-butadiene rubber, were each a control. While the fuel efficiency was improved compared to Examples 3 and 4, the viscosity was significantly reduced, and both low heat build-up and processability could be achieved at a high level.

Although several embodiments of the invention have been described above, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments, their omissions, replacements, modifications, etc., are included in the invention described in the scope of claims and equivalents thereof, as well as being included in the scope and gist of the invention.

Claims (5)

a first mixing step of adding carbon black and a tetrazine compound to the first diene rubber, mixing them in a kneader, and discharging the mixture;
a second mixing step of adding a second diene rubber and silica to the mixture obtained in the first mixing step, mixing the mixture in a kneader, and discharging the mixture. The method for producing a rubber composition according to claim 1, wherein the tetrazine compound is a compound represented by the following general formula (1) or a salt thereof.
In the formula, R ¹ and R ² each independently represent a hydrogen atom, an alkyl group, an alkylthio group, an aralkyl group, an aryl group, an arylthio group, a heterocyclic group or an amino group, each of which is substituted with one or more You may have a group. The method for producing a rubber composition according to claim 1 or 2, wherein the first diene rubber contains styrene-butadiene rubber and the second diene rubber contains natural rubber. The method for producing a rubber composition according to any one of claims 1 to 3, comprising a third mixing step of adding and mixing a vulcanizing agent to the mixture obtained in the second mixing step. Producing a rubber composition by the production method according to any one of claims 1 to 4,
Producing an unvulcanized tire using the obtained rubber composition, and
A method for manufacturing a tire, comprising vulcanizing and molding the obtained unvulcanized tire.